Examples of variable compression ratio internal combustion engines using a multiple-link-type piston crank mechanism are discussed in Japanese Unexamined Patent Application Publication Nos. 2001-227367 and 2002-61501, the contents of which are hereby incorporated by reference. Such variable compression ratio internal combustion engines allow the selection of an optimum compression ratio according to an operation condition. Compared to other internal combustion engines, such variable compression ratio engines may produce less engine emissions, while also increasing the efficiency and output of the engine, and also reducing rotational secondary inertial forces.